The Physicist Who Denies Dark Matter

What struck me was some regularity in the anomaly. The rotational velocities were not just larger than expected, they became constant with radius. Why? Sure, if there was dark matter, the speed of stars would be greater, but the rotation curves, meaning the rotational speed drawn as a function of the radius, could still go up and down depending on its distribution. But they didn’t. That really struck me as odd. So, in 1980, I went on my sabbatical at the Institute for Advanced Study in Princeton with the following hunch: If the rotational speeds are constant, then perhaps we’re looking at a new law of nature. If Newtonian physics can’t predict the fixed curves, perhaps we should fix Newton, instead of making up a whole new class of matter just to fit our measurements.

Read more as Mordehai (Moti) Milgrom, Member (1980–81) and Visitor (1985–86) in the School of Natural Sciences, discusses MOND (Modified Newtonian Dynamics), his theory that he believes fixes Newtonian physics.